Wireless terminals may operate in multiple frequency bands (i.e., “multi-band”) to provide operations in multiple communications systems. For example, Long Term Evolution (LTE) Multiple-Input and Multiple-Output (MIMO) cellular radiotelephones may be designed for operation in nominal frequency bands such as 700-800 Megahertz (MHz), 824-894 MHz, 880-960 MHz, 1710-1850 MHz, 1820-1990 MHz, 1920-2170 MHz, and 2500-2700 MHz.
Achieving effective performance in multiple frequency bands may be difficult. For example, contemporary wireless terminals are increasingly including more circuitry and larger displays and keypads/keyboards within small housings. Constraints on the available space and locations for antennas in wireless terminals can negatively affect antenna performance.
For example, although wireless terminals may include multiple antennas, mutual coupling between different antennas may degrade performance. Moreover, if a wireless terminal uses its chassis as a shared radiator for multiple antennas operating in low frequency bands (e.g., below about one (1.0) Gigahertz (GHz)), then mutual coupling may particularly degrade performance (e.g., in terms of correlation, diversity gain, and capacity) in the low frequency bands.